Implemented recursive & iterative factorial (#9 IP)

Author: CoffeelessProgrammer

Algorithms/Recursion/Basics.ts

@@ -10,11 +10,17 @@ function inception(repeat: number): string {
   return inception(repeat-1);                 // The recursive call should return itself so the calculated value can bubble up
 }
 
-console.log(inception(5));
-console.log(inception(1));
-console.log(inception(-1));
+//---------------------------------------------------------------------
+// ----------                 MAIN PROGRAM                   ----------
+//---------------------------------------------------------------------
+if (import.meta.main) {
 
-// RUN:   deno run Algorithms/Recursion/Basics.ts
+  console.log(inception(5));
+  console.log(inception(1));
+  console.log(inception(-1));
+
+  // RUN:   deno run Algorithms/Recursion/Basics.ts
+}
 
 // --------------------------- Terminal Output: ---------------------------
 // Counter: 5

Algorithms/Recursion/Factorial.ts

@@ -0,0 +1,69 @@
+function calcFactorialRecursive(input: number): number {
+  if (input <= 1) return 1;
+
+  return input * calcFactorialRecursive(input-1);
+}
+
+function calcFactorialIterative(input: number): number | undefined {
+  if (input < 0) return undefined;
+
+  let factorial = 1;
+
+  for (let i=2; i <= input; ++i) {
+    factorial *= i;
+  }
+
+  return factorial;
+}
+
+function validateFactorialInput(input: number): boolean {
+  return input>=0;
+}
+
+function printIterativeFactorial(input: number) {
+  if (!validateFactorialInput(input)) {
+    console.log("Input", input, "is invalid -_-'");
+    return;
+  }
+  console.log('Iterative Factorial', input+':', calcFactorialIterative(input));
+}
+
+function printRecursiveFactorial(input: number) {
+  if (!validateFactorialInput(input)) {
+    console.log("Input", input, "is invalid -_-'");
+    return;
+  }
+  console.log('Recursive Factorial', input+':', calcFactorialRecursive(input));
+}
+
+
+//---------------------------------------------------------------------
+// ----------                 MAIN PROGRAM                   ----------
+//---------------------------------------------------------------------
+if (import.meta.main) {
+
+  printIterativeFactorial(0);
+  printIterativeFactorial(1);
+  printIterativeFactorial(2);
+  printIterativeFactorial(3);
+  printIterativeFactorial(5);
+  printRecursiveFactorial(4);
+  printRecursiveFactorial(0);
+  printRecursiveFactorial(-1);
+  printRecursiveFactorial(170);
+  printIterativeFactorial(171);
+
+  // RUN:   deno run Algorithms/Recursion/Factorial.ts
+}
+
+// --------------------------- Terminal Output: ---------------------------
+// Iterative Factorial 0: 1
+// Iterative Factorial 1: 1
+// Iterative Factorial 2: 2
+// Iterative Factorial 3: 6
+// Iterative Factorial 5: 120
+// Recursive Factorial 4: 24
+// Recursive Factorial 0: 1
+// Input -1 is invalid -_-'
+// Recursive Factorial 170: 7.257415615307994e+306
+// Iterative Factorial 171: Infinity